Answer a business buyer who wants a discount

A business buyer wants a discount. Help me answer.

What they asked: [paste]
What I supply and the current price: [details]
My rough margin: [percentage or amount]
Their volumes and how they pay: [details]

Ask me up to 3 short questions first if anything important is missing. Wait for my answers.

Then:
1. Trade-offs I could ask for in return (bigger volume, longer term, faster payment, fewer deliveries).
2. The sums for each option using my numbers.
3. A reply email that offers a trade-off rather than a straight cut.
4. The point where I should say no, and how.

Use only what I've given you, leave blanks for any price or fact I haven't given, and don't invent anything. UK English. Show the sums; this isn't financial advice.

Stay in this ChatGPT chat. Do not turn on apps or connectors, and do not use memory from another chat.